Corticotropin releasing factor (CRF) is a 41 amino acid peptide that coordinates the overall response of the body to stress. As an agonist of CRF receptors (e.g., CRF1 and CRF2), CRF is well known as the primary physiological secretagogue controlling hypothalamic-pituitary-adrenal (HPA) axis activity which mediates the endocrine stress response. CRF also plays a central role in the autonomic and behavioral responses to stress. Variation in physiological levels of CRF has been correlated with various disorders including depression and anxiety.
Antagonists of CRF receptors have been shown to effectively ameliorate behavioral stress responses in animal models. It is well established that systemic administration of CRF1 receptor antagonists leads to anxiolytic and antidepressant effects in rodents. Animal model evidence also shows that CRF1 antagonists can help alleviate the symptoms of drug withdrawal, stress-induced seizures, and certain inflammations. A role for CRF has also been postulated in the etiology and pathophysiology of Alzheimer's disease, Parkinson's disease, Huntington's disease, progressive supranuclear palsy, and amyotrophic lateral sclerosis as they relate to the dysfunction of CRF neurons in the central nervous system. Eating disorders, such as anorexia nervosa, have also been linked to elevated levels of CRF.
Though widely dispersed throughout the central nervous system, CRF receptors are also found in peripheral systems including glandular, vascular, gastrointestinal, and immune system tissues. Accordingly, CRF antagonists are believed to have potential in treating numerous other disorders outside the central nervous system. Some CRF-related disorders of peripheral systems include, for example, hypertension, tachycardia, congestive heart failure, stroke, irritable bowel syndrome, post-operative ileus, and colonic hypersensitivity. Studies have indicated that CRF1 antagonists may also be useful as hair growth stimulators.
The compound 4-(bis(2-methoxyethyl)amino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-[1,5-a]-pyrazolo-1,3,5-triazine has been identified as an effective CRF receptor antagonist that can be useful in treating, for example, the above-named disorders. This compound is reported in U.S. Pat. No. 6,124,289 which is incorporated herein by reference in its entirety.
While numerous CRF receptor antagonists have been discovered, like the above compound, few typically possess the characteristics that are satisfactory for the preparation of stable pharmaceutical compositions. Melting point, hygroscopicity, stability, solubility, crystallinity, bioavilability, and handling characteristics are among the numerous properties that need to be considered in preparing medicaments that can be effectively administered. Accordingly, there is an ongoing need to prepare compounds with physical and chemical properties that are both physiologically acceptable and suitable for preparing reproducible pharmaceutical formulations. The salts of the present invention helps fulfill this and other needs.